Yellow azo dye and process of making same.



ITED STATES PATENT OFFICE,

FRANZ SOHOLL, OF HOOHST-ON-THE-MAIN, GERMANY, ASSIGNOR TO THE FARBWERKE, VORMALS MEISTER, LUOIUS dz BRUNING, OE SAME PLACE.

YELLOW AZO DYE AND PROCESS OF MAKING SAME.

SPECIFICATION forming part Of Letters Patent No. 656,859, dated August 28, 1900. Application filed June 23, 1900. Serial No. 21,301. ($pecimensl) To all whom, it may concern.-

Beit known that I, FRANZ SoHoLL, Ph. D., a citizen of the Empire of Germany, residing at H6chst-on-the=Main, Germany, have invented certain new and useful Improvements in the Manufacture of Substantive Dyestuffs for Cotton Fast to Alkali, Acid, and Light, of which the following is a specification.

I have found that a very beautiful easilysoluble yellow dyestuff for cotton may be obtained with good yield by combining diazotized primulin with 1-para-sulfophe11yl-3-methyl-5-pyrazolone. To manufacture this dyestuff, I employ the diazotized sulfonic acid of the primulin base obtained byheating paratoluidin with sulfur, on the one hand, and 1- p'ara-sulfophenyl-3-methyl-5-pyrazolone, on the other hand.

Example: Seventy-five kilos of primulinsulfonic acid and seven kilos of sodium nitrite are dissolved in one thousand liters of Water. This solution is run While stirring into thirtysix kilos of hydrochloric acid (thirty percent. strength) and about one hundred liters of water. After a few hours the diazo compound thus obtained is run into a solution of twenty-seven kilos of l-para-suL fophenyl-S-methyl-5-pyrazolone and thirty kilos of sodium carbonate in about four hundred liters of water. The combination is soon completed. The dyestuft' is salted out. The

dyestuff thus obtained by combining one molecular proportion of diazotized primulinsulfonic acid with one molecular proportion of l-para-sulfophenyl-3-methyl-5-pyrazolone is an orange-yellow powder very easily soluble in cold water with a reddish-yellow color,

becoming redder on addition of caustic alkali, soluble with difficulty in alcohol,and insoluble in benzene, petroleum, and other. It 40 separates from its aqueous solution on addi tion of mineral acids in the form of yellow flakes, is soluble in concentrated sulfuric acid with a light-yellow color, and dyes cotton in a neutral or alkaline bath yellow.

Having thus described my invention, I claim- 1. As a new product, the new yellow dyestuff obtained by combining one molecular proportion of diazotized primulinsulfonic 5o acid with one molecular proportion of ll-parasulfophenyl-3-methyl-5-pyrazolone, being an orange-yellow powder easily soluble in cold water with a reddish-yellow color, soluble with difficulty in alcohol, insoluble in benzone, petroleum and ether, separating from its aqueous solution on addition of mineral acids in the form of yellow flakes, and dyeing cotton in a neutral or alkaline bath yellow, substantially as set forth.

2. The herein-described process of manufacturing an azo dyestuif directly dyeing cotton yellow, which consists in allowing diazotized primulinsulfonic acid to act upon 1- para-sulfophenyl-3-n1ethyl-5-pyrazolone,sub- 65 stantially as set forth.

In testimony that I claim the foregoing as my invention I have signed my name in presence of two subscribing witnesses.

FRANZ SCHOLL.

With esscs HEINRICH HAHN, ALFRED Bmsnors. 

